Hood scoop fluttering? ??

R

ridinpowder

New member
Ok so I have a new 4runner Trd and I have hood flutter that drives me crazy. The dealership took a look at it and said hmmm well not sure what to say. WTF?? OKay so any way is it me or does anyone with a hood scoop hood notice it? It's up towards the windshield and it's just sits and flutters even at High speeds on the freeway. And adjusting the little rubber stops at the front (under the hood) makes no difference. So my question . Is that normal? Seems very untoyota like, my landcruisers hood doesn't look like its ready to fly away. Any help or comments?
 
Register to hide this ad
Yes, it's normal. The hood is not structural in any way, just there to cover the engine, so they made it as light as possible.

There are 2 things (that I know of) you can do to "fix" it, which I have done. 1 is to put sound deadening material on the underside, which increases its weight and changes its resonant frequency. The other is to cover it with vinyl wrap, which also gets rid of the annoying glare, if you get a matte finish.
 
Yes mine does it too. I believe that the front bumper radiator area opening is so big and flat on the front of the truck that when driving at high speeds the large amounts of wind forced into the engine bay find the path of least resistance and flood the upper part of the hood area which in turn the tries to find an exit flow area, which would be cowl area that doesn't have an equal exit flow to the intake of air, causing the thin ass flexible aluminum hood to waddle back and forth like it's got Parkinson's... At least that's my take on it.
 
FWIW - My SR5 hood (no scoop) also undulates somewhat uncomfortably at freeway speeds - but you get used to it. I don't see how the paint can take all the flexing w/o eventually cracking/flaking, but I guess it's relatively minor stress in the end.

:cool:
 
Jeremy556 said:
Yes, it's normal. The hood is not structural in any way, just there to cover the engine, so they made it as light as possible.

There are 2 things (that I know of) you can do to "fix" it, which I have done. 1 is to put sound deadening material on the underside, which increases its weight and changes its resonant frequency. The other is to cover it with vinyl wrap, which also gets rid of the annoying glare, if you get a matte finish.
Click to expand...
No sound deadening material make a difference. A local guy with a TE have put some under it and told me it helped a lot on the fluttering. Also made the interior quieter, but not that much...
 
Its a TRD Pro hood which has been shaved to racing depth to encourage high speed maneuvering! I understand the fluttering also reduces chances of whistling by disrupting the airflow over the hood. :behindsofa:

(The above statement has NOT been certified or endorsed by any professional employee of TRD, Toyota, or 1engineer's professional background)
 
Last edited:
2010 Trail with scoop. I used expanding foam in the reinforcing under the hood. Use masking tape on the edges and holes and shot the foam into the channel. Gotta be careful and not put too much. The sucker really expands and can bow the hood if you put too much. Let it dry and trimmed off the excess. Almost no flex and not so irritating in bright sunlight. Adding some Dynamat type sound deadener would probably eliminate the rest of the vibration.
 
Am I missing something here? Is there no way to secure the scoop with 3M automotive trim grade double sided tape? As long as you have a lip on the hood on which the scoop sits it will do the job very nicely. Remove the "scoop" (because lets face it, its a non-functional piece of jewelry), apply the tape to the lip, press said scoop into tape and tighten it down. It'll be rock solid.

Disclaimer:
I have no clue how the scoop mounts and I'm just assuming its similar to the way Subaru mounts theirs on my WRX and my wife's Forester XT.
 
Bootleg said:
Am I missing something here? Is there no way to secure the scoop with 3M automotive trim grade double sided tape? As long as you have a lip on the hood on which the scoop sits it will do the job very nicely. Remove the "scoop" (because lets face it, its a non-functional piece of jewelry), apply the tape to the lip, press said scoop into tape and tighten it down. It'll be rock solid.

Disclaimer:
I have no clue how the scoop mounts and I'm just assuming its similar to the way Subaru mounts theirs on my WRX and my wife's Forester XT.
Click to expand...

Other than the plastic insert in the front the scoop on the Trail is part of the stamped steel hood. The OP is referring to the fact that the hood moves around a fair bit over bumps or when hit by, say the wind gust from a semi going the other direction at highway speed. It's the same problem with all 3 models of the 5th Gen. Not just the ones with scoops.
 
3wbdriver said:
Other than the plastic insert in the front the scoop on the Trail is part of the stamped steel hood. The OP is referring to the fact that the hood moves around a fair bit over bumps or when hit by, say the wind gust from a semi going the other direction at highway speed. It's the same problem with all 3 models of the 5th Gen. Not just the ones with scoops.
Click to expand...

Hence the disclaimer.Thanks for enlightening me. :thumb:

For what its worth the hood on my SR5 moves around a fair bit at highway speeds as well.
 
For what it is worth, the hood scoop is sort of a carry-over these days, though it was functional at more than one point in the 4Runner's history; just not for the US.

The 4th gens came with a 3.0L 1KD-FTV Diesel option and the scoop funneled air to the intercooler set-up. But they left it untouched for the Sport Edition Trim on the US 4th Gens, despite not carrying the diesel over to the US. I think at this point they just kept it mainly for looks on the 5th Gen, unless they plan on a diesel sometime in the future (doubtful.) Ironically, you'd think the Tacoma would have shared that option as well, but the Tacoma is really only a North American vehicle; the Hilux platform does the diesel duty overseas (yet they retained the hoodscoop the same as the 4th & 5th gens.)
 
This afternoon, I drove mine to an undisclosed MPH (the speed I was going some things on my body was fluttering...scaring self) to see if mine would flutter because I had never noticed any movement described at all.
***It was rock solid to my amazement.***
Could the solution be checking all of the rubber bumps to make sure they are making good contact?
 
[MENTION=103267]Saker[/MENTION]

Obviously you have stumbled upon the correct solution. By increasing forward momentum exponentially you have created a deflective airfoil effect that pushes a large majority of the pressure front away from the structurally pliable section of the hood. This allows the pressure waves to pass over the pliable membrane of the hood scoop in a resonance frequency that creates a harmonic equalization similar to a null-effect constant that occurs in low pressure zones (think how glass smooth water gets when it rains.) This barometric anomaly results in a synchronous effect that belies the pliable nature of the hood scoop and instead permeates the illusion of rigidity.

...


In other words, you went so fast the damn hood scoop was too scared to move. :tongue1:

Post Note-

[MENTION=82005]jere[/MENTION]mey556 [MENTION=66316]1engineer[/MENTION] How's that for nonsensical drivel! :flame:

LoL I probably shouldn't post when drinking booze.
 
Classic. Keep it up and you will fit right in especially if you go into government service or better yet, civil engineering.
 
BlackWorksInc said:
[MENTION=103267]Saker[/MENTION]

Obviously you have stumbled upon the correct solution. By increasing forward momentum exponentially you have created a deflective airfoil effect that pushes a large majority of the pressure front away from the structurally pliable section of the hood. This allows the pressure waves to pass over the pliable membrane of the hood scoop in a resonance frequency that creates a harmonic equalization similar to a null-effect constant that occurs in low pressure zones (think how glass smooth water gets when it rains.) This barometric anomaly results in a synchronous effect that belies the pliable nature of the hood scoop and instead permeates the illusion of rigidity.

...


In other words, you went so fast the damn hood scoop was too scared to move. :tongue1:

Post Note-

[MENTION=82005]jere[/MENTION]mey556 [MENTION=66316]1engineer[/MENTION] How's that for nonsensical drivel! :flame:

LoL I probably shouldn't post when drinking booze.
Click to expand...

[MENTION=66389]BlackWorksInc[/MENTION],

Now I totally understand the concept. :faint:
One thing, my SR5 doesn't have a hood scoop. I wanted to do the test to see if it is only the T4R's with the HS.
 
Heres a fun-fact. My brother's looking at audi S4's and we checked one out at a dealer the other day. The salesman popped the hood and started rocking the whole car back an forth with it, claiming a special type of seam welding made audi hoods a structural component of the vehicle.. first thing I thought of was my t4r's hood flutter. He then pursued to open the door and swing back and forth on it.. ditto on explaining the seam welding.

Although impressive it was a little over the top. For an suv's intents and purposes I'd rather have strength down below in the frame.. but I understand how this type of engineering could make a difference in the performance car category. It doesn't bother me at all that the hood moves a little, it saves weight and I'm not worried at all that it's going to come loose. My Rubicon's hood fluttered like mad on the freeway but not because it was lightweight, it's cause the rubber latches holding it down were too pliant of a compound.. that was a different story.
 
You must log in or register to reply here.

Members online

Total: 301 (members: 3, guests: 298)

Forum statistics

Threads
278,309
Messages
3,554,075
Members
248,016
Latest member
Advally Service

Share this page

Trending content

Back
Top